Extended Data Fig. 2: The herbivory versus metabolic costs of fixation across leaf lifespan.
From: Widespread herbivory cost in tropical nitrogen-fixing tree species
How the fixation-associated herbivory costs and metabolic cost of fixing nitrogen vary over leaf lifespan. Costs shown as a percentage of annual NPP per year, using the mean herbivory and leaf area for fixers and non-fixers up until the maximum leaf lifespan for shade species recorded in the 50ha plot on Barro Colorado Island (BCI). The photosynthetic opportunity cost was calculated as the accruing photosynthesis forgone until the end of the leaf lifespan (dark blue line). The structural carbon cost remained constant since the cost per year would not vary with leaf lifespan (red line). The metabolic cost represents the percentage of NPP required to replace either 40% of leaf nitrogen (at 40% light, orange line) or 0% (at 16% light, light blue line) paying six grams of carbon per gram nitrogen over one year, depending on leaf lifespan. The mean leaf lifespan for shade species in the BCI 50ha plot is 21.65 months (green line). These values differ from Fig. 3b since they are at the leaf level, use mean values as parameter estimates and consider variation in leaf lifespan.
